In the rural Belgian town of Smetlede, polycarbonate—a type of extra-strong plastic—is often used to sheathe porches and verandas. When architect Indra Janda designed what she calls a “garden room” on her parents’ estate, the humble, inexpensive, and easy-to-work-with material was a natural choice. “But I wanted to use it in a different kind of way,” Janda says. She hand-cut sheets of polycarbonate into 15¾-inch square shingles and clad an entire timber structure—a gabled roof and walls—with them. The 484-square-foot room offers a cool respite from summer sun and a warm place to relax in winter.